tools-only Vectorize Gotchas
Critical Warnings
Async Mutations
Insert/upsert/delete return immediately but vectors aren't queryable for 5-10 seconds.
Batch Size Limit
Workers API: 500 vectors max per call (undocumented, silently truncates)
// ✅ Chunk into 500
for (let i = 0; i < vectors.length; i += 500) {
await env.VECTORIZE.upsert(vectors.slice(i, i + 500))
}
Metadata Truncation
returnMetadata: "indexed" returns only first 64 bytes of strings. Use "all" for complete metadata (but max topK drops to 20).
topK Limits
| returnMetadata | returnValues | Max topK |
|---|---|---|
"none" / "indexed" |
false |
100 |
"all" |
any | 20 |
| any | true |
20 |
Metadata Indexes First
Create BEFORE inserting - existing vectors not retroactively indexed.
# ✅ Create index FIRST
wrangler vectorize create-metadata-index my-index --property-name=category --type=string
wrangler vectorize insert my-index --file=data.ndjson
Index Config Immutable
Cannot change dimensions/metric after creation. Must create new index and migrate.
Limits (V2)
| Resource | Limit |
|---|---|
| Vectors per index | 10,000,000 |
| Max dimensions | 1536 |
| Batch upsert (Workers) | 500 |
| Indexed string metadata | 64 bytes |
| Metadata indexes | 10 |
| Namespaces | 50,000 (paid) / 1,000 (free) |
Common Mistakes
- Wrong embedding shape: Extract
result.data[0]from Workers AI - Metadata index after data: Re-upsert all vectors
- Insert vs upsert:
insertignores duplicates,upsertoverwrites - Not batching: Individual inserts ~1K/min, batched ~200K+/min
Troubleshooting
No results?
- Wait 5-10s after insert
- Check namespace spelling (case-sensitive)
- Verify metadata index exists
- Check dimension mismatch
Metadata filter not working?
- Index must exist before data insert
- Strings >64 bytes truncated
- Use dot notation for nested:
"product.category"
Model Dimensions
@cf/baai/bge-small-en-v1.5: 384@cf/baai/bge-base-en-v1.5: 768@cf/baai/bge-large-en-v1.5: 1024